Ordinary heat radiators that are used in actual practice for radiating heat generated in semiconductor ICs and other electronic components have a plurality of pectinate heat-radiating fins formed perpendicularly on a base. The heat radiator radiates heat outward via the heat-radiating fins of the heat radiator by direct or indirect contact with an electronic component or the like. The heat radiator is generally manufactured by extruding or casting an aluminum metal material having a high coefficient of thermal conductivity.
Methods of manufacturing heat radiators on which heat-radiating fins are formed by using a cutting tool are disclosed in JP-A 2001-156224 (Patent Document 1) and JP-A 2005-142247 (Patent Document 2). In the method for manufacturing a heat radiator described in Patent Document 1, a heat-sink material is used that is composed of an extruded aluminum alloy on which is formed a jetty-shaped machining portion for forming fins on a top surface of a substrate. A plurality of fins is formed by using a bit or another cutting tool to gouge the fin-forming machining portion.
In the method for manufacturing a heat radiator described in Patent Document 2, a hoop-shaped metal plate having a high coefficient of thermal conductivity and a cutting tool on which a blade section is formed at the leading edge side in the direction of movement are moved relative to each other at a prescribed angle, and a plate-shaped heat-radiating fin is integrally formed upright by gouging the hoop-shaped metal plate. Next, the hoop-shaped metal plate and the gouging tool are moved relative to each other from the upstream side at a distance of the formation pitch from the machining surface on which the heat-radiating fin has been formed upright, and the next plate-shaped heat-radiating fin is integrally formed upright by gouging the hoop-shaped metal plate. Afterward, a plurality of heat-radiating fins is successively formed on the hoop-shaped metal plate by sequentially repeating the gouging step.
The plurality of fins described in Patent Document 1 is a plurality of fins formed at the same height on the surface of heat-sink material. When attempting to form fins of the same height, first, a sloped surface 101 must be formed on a leading edge portion 100a of a fin-forming machining portion 100, as shown in FIG. 7. The sloped surface 101 is formed by cutting the fin-forming machining portion 100a plurality of times using a cutting tool 102, but low and thin fin-shaped scraps 103 are inevitably generated by cutting.
Ordinarily, cutting oil is applied to the fin-forming machining portion 100 and the cutting machine tool 102 when the fins are gouged out. There are occasions when the scraps 103 are thin and therefore adhere to the fin-forming machining portion 100 and the cutting tool 102 after being cut off from the heat-sink material, as shown in FIG. 8. Even when air or the like is used in an attempt to remove the adhering scraps 103, the scraps 103 are thin and therefore adhere to the cutting tool 102 and other blade surfaces because of the machining oil, and sometimes cannot be removed. In the particular case that the scraps 103 adhere to the surface of the fin-forming machining portion 100 in a state in which the scraps are sandwiched between the surface of the fin-forming machining portion 100 and the cutting machine tool 102, as shown in FIG. 8, fins cannot be gouged out, or are deformed and are produced as defective fins.
In the method of forming plate-shaped heat-radiating fins disclosed in Patent Document 2 as well, there are occasions when removing thin, fin-shaped scrap becomes difficult in the same way as in Patent Document 1 because low fin-shaped scrap is generated at one end of the metal plate on hoop-shaped metal plate when heat-radiating fins are formed from one end of the hoop-shaped metal plate. Accordingly, the fin-shaped scraps are sandwiched between the surface of the hoop-shaped metal plate and the cutting tool, and a problem occurs in that the heat-radiating fin that is subsequently formed is formed in a deformed state, or a problem occurs in that the next heat-radiating fin cannot be gouged out.
Patent Document 1 Japanese Laid-open Patent Application No. 2001-156224
Patent Document 2 Japanese Laid-open Patent Application No. 2005-142247.